Minimally invasive surgical methods are familiar, as are the instruments they employ, in which at least one degree of freedom is actuated by the motor, offering the advantage that, by selecting an appropriate motor, e.g. a stepper motor, as well as a suitable transmission ratio, it is possible to obtain very well-measured and fine-tuned movements of the work piece (that is, the inserted part being worked with), so that the impacts of unintentional hand movements or tremors can be reduced.
Currently used microsurgical instruments, for example for laparoscopy, consist as a rule of a work piece with a shaft and a scissors or forceps type of working device on its distal end and with a handle by which the degrees of freedom of the working device are controlled. As a result, the work pieces, for example, offer the degrees of freedom of opening/closing of the members of the working device, rotation about the longitudinal axis and pivoting of at least a longitudinal portion of the shaft. It is possible to operate individual functions, or all functions, by motorized power.
Patent EP 2 837 354 A1 discloses a microsurgical instrument in which a distal shaft section is pivoted by means of an electric motor in the handle, which drives a bevel gear. On a secondary shaft powered by the drive bevel on the output side, a spur gear is mounted non-rotatably and engages in two toothed racks. Upon rotation of the spur gear, the one toothed rack moves forward and the other backward. One half-shaft is in turn connected to each of the toothed racks, so that the two half-shafts together are conducted in an outer shaft, which extends to the working device. The half-shafts extend to the anglable distal end and serve as a power transmission element for the angulation.
The electric motor there takes the form of a separate component and can be coupled with the handle only if the toothed wheels of the engine output shaft and the input shaft of the handle are situated at an appropriate angle to one another. For this reason, to couple the motor, if necessary the distally anglable portion must be deflected by hand and the toothed wheels thus brought into an engaged position. As soon as the toothed wheels are engaged, the electric contact is established, and contacts on the engine block and on the base body of the handle are connected through the installation movement of the engine block.